1. Field of the Invention:
The present invention relates to a water warming method and an apparatus therefor which are capable of warming the water contained in a water tank very quickly.
2. Description of the Related Art:
Japanese Utility Model Publication No. 52-18440 discloses a submerged heater apparatus which is capable of heating a liquid by ejecting high temperature combustion gas directly into the liquid and thereby conducting a direct heat exchange between the high temperature combustion gas and the liquid. In this heater apparatus, a high temperature combustion gas ejecting pipe also serving as a combustion chamber which is provided coaxially with respect to a mixing chamber of a burner is put into a liquid contained in a liquid tank to a suitable depth at the central portion of the tank, and a high temperature combustion gas which is obtained in the pipe is ejected into the liquid from a large number of small holes formed in an umbrella type diffusing plate provided at the end of the pipe, so as to generate bubbles in the liquid. The liquid is vigorously stirred by the bubbles generated, and is heated by virtue of direct heat exchange conducted between the bubbles and the liquid.
However, the conventional heater apparatus of the above-described type has a disadvantage in that, since high temperature combustion gas obtained in the burner is ejected directly into the liquid through the ejecting pipe placed in the liquid, the ejecting pressure of the combustion gas must be raised to a value equivalent to a water head or above to enable the gas to be ejected into the liquid, requiring a special pressure raising device for raising the pressure of the ejecting gas to a sufficient value. This increases the size and production cost of the heater apparatus and limits the application field of the apparatus.